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    <meta charset="UTF-8">
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    <title>Document</title>
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<body>
    <script>
        /***
         *  强转数字：
         *  Number('123')
         */

        var a = '123';
        console.log(+a, typeof +a);  // +a ===> Number(a)

        console.log(1 + Number(a));
        console.log(1 + +a);

        console.log(a-0, typeof (a-0));

        console.log(1*a,typeof (1*a));

        console.log(a/1, typeof (a/1));


    </script>
</body>
</html>